Back in the late 1980s, scientists suggested that the sudden spike in allergy sufferers was the result of living in sterile homes and overzealous hygiene practices. Our immune systems, went the thinking, weren't being exposed to potentially important infections. A recent report, however, indicates that this "Hygiene Hypothesis" is false and that no link exists. Instead, the researchers have presented a new theory — one that links allergies and other diseases to our lack of exposure to human, animal, and environmental microbes.

This new report comes to us from the International Scientific Forum on Home Hygiene (IFH), an initiative that's being led by Sally Bloomfield and Rosalind Stanwell-Smith. They argue that the name "Hygiene Hypothesis" is misleading, and that it's giving people a false sense of why allergies are emerging at such significant rates. Moreover, as the researchers stated through a press release, "If worrying about 'being too clean' results in people needlessly exposing themselves and their children to pathogens that can make them ill, this would clearly be dangerous."

Indeed, the conventional thinking over the past twenty years was that a lower incidence of infection in early childhood (mostly through unhygienic contact with other siblings) could be an explanation for rising levels of allergic diseases and asthma. The authors caution, however, that no causal link has ever been properly established linking infectious diseases to the immune system's ability to ward off allergies.

That said, the authors do acknowledge the importance of microbes. And in fact, their research indicates that modern living has resulted in dangerously low exposure levels to critical microbial "old friends" that are not only important for the proper regulation of allergies, but for warding off chronic inflammatory diseases such as Type 1 diabetes and multiple sclerosis.

And indeed, the suggestion that we should expose ourselves to the right microbes is consistent with the latest thinking on proper gut flora maintenance and the overall integrity and diversity of the human microbiome; the science is increasingly showing that microbes play a crucial role in the regulation of our immune systems.

The microbes in question include those that humans would have been regularly exposed to prior to the 19th century, and most prominently during the Paleolithic Era. The authors argue that these microbes are no longer present in our homes — and not because of our cleaning practices (though that's hard to believe). They suggest that modern homes have a lower diversity of microbes, but still contain bacteria, viruses, fungi, moulds and dust mites.

And as for the microbes we should be exposing ourselves to, the researchers suggest that rural environments contain "the right kind of dirt." As to how we could actually go about this, however, is a question that remains unanswered. Read the entire report.